How smart can an animal get? Ask Irene Pepperberg's parrots. They'll be glad to discuss the subject with you.

Alex, age 23, and Griffin, age 4, are hell on decor. Thanks to them, the laboratory-cum-home of these impish African Grey parrots looks as if a miniature tornado has blown through. Strewn about are pieces of fruit from discarded snacks, mangled toys, and a huge mound of cardboard cartons demolished with great relish by Alex.

Psychologist Irene Pepperberg, the birds’ caretaker, maintains an amused tolerance about her two charges partly because they have richly rewarded her serious scientific inquiry into the intelligence of animals. For more than 20 years, her research has insistently challenged the idea that humans alone are capable of real thought and real language. In a series of experiments that withstand rigorous and even hostile scrutiny, Alex and Griffin have shown themselves intelligent enough to comprehend and juggle abstract images of the objects that make up their world—skills once thought to be the exclusive property of humans.

Under Pepperberg’s tutelage, the parrots have learned to speak English so clearly they’d delight even a fussy speech expert. But the value of this work goes far beyond experiments in voice training. These parrots aren’t just parroting—they associate specific words with specific objects, and they have learned to identify a number of different colors, shapes, and materials. Show Alex two triangles, one yellow and one blue, and ask him what’s the same about them. He’ll answer, “Shape.” Ask him what’s different, and he’ll say, “Color!”

Until Pepperberg began this research in the 1970s, few scientists had studied intelligence in parrots, and few do today. Most inquiries have instead focused on monkeys, chimpanzees, gorillas, and dolphins, all of which are much more difficult to raise, feed, and handle. Pepperberg especially likes parrots because, like humans, they’re smart, long-lived (often up to 50 years), social animals that depend on communication for survival. And, best of all, to communicate with people, parrots don’t need devices built with buttons to push, and they don’t need to be taught sign language: They speak plain English. Nobody knows why parrots can do this, or exactly how they do it. But they can clearly get their two cents in despite having a brain the size of a walnut.

Even the most skeptical visitor to Pepperberg’s lab is sure to be taken aback by what the birds can do. When Alex, for example, wants to visit a favorite atrium near the lab, he orders, “Go see tree!” And some of his communications are fresh—new words and phrases he hasn’t been taught. Once, for example, as two of his student trainers prepared to leave the lab at the end of a day, Alex admonished: “You be good. See you tomorrow!”

HOW TO TALK TO A PARROT

“The critical thing to understand is that these birds are extremely intelligent,” says Irene Pepperberg. “In the wild, they spend huge chunks of time breaking things open, looking for food, and they probably fly a couple of miles every day foraging. When they sit in a cage all day, it’s like putting a person in solitary confinement. Give them a big cage with interesting things in it; give them a lot of attention and a lot of supervised freedom.”

To train a parrot to talk, do not park yourself in front of it, robotically repeating “Hello.” The bird may eventually imitate you, but how can it know what the word means? Instead, Pepperberg advises, “Find a friend and invite her over for coffee and cake.” Then get to work. With the parrot observing, show the friend a key and say “key” at the same time.

Then hand the key over when the friend says the word clearly. Do it a few times with the friend, then do the same with the bird, handing over the key as soon as it repeats the word comprehensibly. A bird taught this way is more likely to learn the word’s meaning as well as the word itself. And it’s a lot more fun to communicate with a pet than to listen to it parrot meaningless words or phrases. —M.C.

It’s not just what they the parrots say that makes them seem eerily human; it’s the level of intelligence they easily demonstrate. Consider Griffin’s performance on a test Pepperberg devised to see whether the birds could use a mirror image of an object to manipulate it. Children don’t typically master that skill until they’re three years old. In the experiment, a nut is concealed underneath a lid on a box. The nut is attached to a wire that leads up through a slit in the lid and connects to a paper clip the parrot can yank. The slit branches out into three tracks, each of which ends in a hole through which the nut can be pulled. The trick is that two of the three slits are blocked by obstructions that can only be seen by looking in a mirror that reflects a backward view of what’s inside the box. Most humans who try to solve the puzzle are baffled, but Griffin, watching intently from his perch on the lab counter, might demand to be brought over, peer into the mirror for perhaps half a second, triumphantly zip the nut down the right track, jerk it up through the opening, and grab it.

Although Irene Pepperberg has always loved animals, she chose chemistry as her field in graduate school at Harvard University. There, in the early 1970s, she happened to see a television documentary about how animals learn. Like a number of researchers at the time, she became fascinated by the question of just how smart animals are and if they could learn to communicate with humans. While finishing up her chemistry degree, she began taking courses in animal behavior, psychology, and communication In 1977 she acquired one-year-old Alexl. he became the center of her research in a small lab at Purdue University.

Much of the animal-intelligence research of that era ultimately foundered before the onslaughts of skeptics. Most notable was Washoe, a chimpanzee who became world-famous for her apparent mastery of American Sign Language. But observers of Washoe objected that the researchers who worked with her were giving subtle cues and generously interpreting ambiguous gestures as signs for words. “It’s so easy to overinterpret when you have a bird that says, ‘I’ll see you tomorrow,’ ” says Pepperberg. “I’ve got enough anecdotal data like that to fill a book. But what’s really referential?” What, in other words, constitutes proof that the bird knows what it is saying? The history of science is littered with animals that seemed to be displaying extraordinary brainpower but were just responding to unconscious prompts from owners and trainers.

To avoid such pitfalls, Pepperberg designs experiments with the care of a hard-nosed skeptic. For example, when an experiment demands that Alex learn a new word like “none,” Pepperberg waits until the parrot’s pronunciation is so unambiguous that different observers agree 90 percent of the time on what he’s saying. That ensures that an experimenter eager for Alex to succeed won’t mishear a slurred random utterance as a right answer. She also strives to avoid the possibility that a correct response is merely conditioned—automatic behavior generated by the anticipation of a reward. So experimenters vary their repertoire of questions to make sure that Alex is responding to the content of the question and making intelligent discriminations. And to avoid the possibility that the experimenter’s body language might be prompting his answers, students who test Alex are never the same as those who taught him the words and concepts involved. As a result, Pepperberg’s work has won accolades for its persuasiveness from the likes of Oxford animal behaviorist Marian Stamp Dawkins, an authority on animal consciousness and a skeptic about many studies in the field.

Sometimes, human error offers the birds an opportunity to show how smart they are. Roughly 5 percent of the time, for example, student questioners slip up and scold Alex with a “No!” when he has in fact given the correct answer. When this occurs, Alex tends to stick to his guns and repeat the right answer. Eventually the examiner comes to her senses, and Alex gets the reward he deserves.

Pepperberg is careful to point out that such experiments have stimulated Alex and Griffin to master intellectual tasks both far different from and possibly harder than they might achieve in the wild. And that is perhaps the most promising aspect of her research in the long term. “I don’t want to say they’re learning English,” she says, “because we can’t get inside an animal’s brain and can’t know if its experience of English is exactly the same as ours. But they have learned a communication system that’s completely alien to them.” She argues that this achievement alone is significant—and not just because it challenges dogma about animal intelligence. The way she has trained parrots to master skills outside their natural repertoire—which she calls “exceptional learning”—also serves as an interesting model for human instruction.

Her training technique is interactive, using a model/rival mode. And it is simple: Both animals and people learn more readily when they can observe and even compete with others learning at the same time. The best results come if, instead of being harangued by a teacher, the pupil watches a tutor coaching someone else. The pupil learns by noting that the teacher rewards the student for correct answers and rebukes for wrong ones. The technique, pioneered by Dietmar Todt at the University of Freiburg in the 1970s, worked quickly when Pepperberg tried it with Alex. He caught on rapidly as she taught the undergraduate who served as a model. Alex began competing with the student for Pepperberg’s attention and approval. The model/rivalstrategy worked so well for Alex that it has been successfully adapted for helping with developmentally disabled children learn.

By the late 1980s, Alex had learned the names of more than 50 different objects, five shapes, and seven colors. He’d also learned what “same” and “different” meant—a step so crucial in human intellectual development that it has become a staple of Sesame Street shtick. Show Alex two objects of different shape, color, and material, and then ask him “What’s same?” He’ll answer, “None!” Thus he appears to understand not only what is the same or different but also an even more abstract concept—absence. Alex has become so skilled that, in one of Pepperberg’s projects, he has been promoted to the position of tutor. “We want to see if Alex can work as a tutor for Griffin,” Pepperberg explains. “Partly we got Griffin to replicate our work with Alex, to prove he wasn’t some kind of avian Einstein.”

THE CASE OF CLEVER HANS

Hans was a horse with a head for numbers. In the early 1900s, he and his trainer, Wilhelm von Osten, became well known for Hans’s performances. When someone in the audience asked Hans to add four and three, the horse would stamp his hoof seven times.

But after carefully observing Hans in action, Oskar Pfungst, a psychologist from the University of Berlin, concluded that the horse’s talent didn’t lie in number-crunching. Pfungst noted that as long as the questioner knew the answer, Hans would respond correctly. Only when the questioner did not know the answer or was hidden behind a screen did the horse fail. The key to Hans’s extraordinary ability, Pfungst finally realized, was his attention to subtle physical cues. For example, when someone asked Hans to add six and five, he began stomping. But once Hans had stomped 11 times, the questioner would relax.

The change in posture was too subtle for most observers to notice. And the questioners (including Pfungst when he tried to test Hans) were unaware of it. But Hans picked up the unintended signal and responded. It wasn’t equine math. It was the horse’s uncanny sensitivity to his questioners’ unconscious cues.--M.C.

To demonstrate, Justin, one of Pepperberg’s undergraduate assistants, instructs Griffin and Alex to hop up on the work perch. As in many a human classroom, things get off to a balky start. Griffin seems cranky, insistently croaking, “Wanna go back.” He has spent most of this morning idly shoving a metal spoon back and forth across the countertop and wants to return to the lab counter to play. Justin displays a ring and asks: “What toy, Griffin?” Griffin answers “Wood!” and Alex unhelpfully pipes up with “Rock! Rock! Rock!” A couple more trials follow, in which Griffin correctly identifies cork, wood, and wool (which he pronounces with a sirenlike flourish “Wooh-ull!”). Alex sits taciturnly by. As the experimental session progresses, both Alex and Griffin seem to slide into the spirit of things, falling almost naturally into the model/rival mode. Justin displays a key and asks, “What toy?” Griffin doesn’t answer at first, but when Alex barks, “Key!” Griffin follows suit. When Griffin doesn’t respond to a toy truck, Alex chimes in with a quite fed-up-sounding “Truck! Truck!”

Pepperberg’s instructional techniques have been so successful that they’ve now attracted the interest of researchers in artificial intelligence. She recently worked with computer scientists at the Massachusetts Institute of Technology to help develop software that can learn or than can be used to help others learn. “It’s a lot simpler to model a parrot’s learning than a person’s,” Pepperberg says. But she believes that computer software could be written to respond to—maybe even “learn” from—the interplay of correct answers and mistakes that makes up the model/rival system.

Whether its promise is for people or computers, Pepperberg’s research is forcing psychologists to rethink the boundaries between animals and humans. The thought processes of Alex and Griffin may approximate our own a lot or a little, says Pepperberg, but it’s getting well-nigh impossible to deny their intelligence.

A recent incident caught on videotape during a model/rival session illustrates the point: Griffin, while trying to say “paper,” splutters “ay-uhr.” Alex, seemingly pushed to the limits of his patience, peremptorily orders Griffin to “Talk clearly!”